Power converters are used nowadays in many technical applications. Thus, for example, with centrifugal pumps which are applied as heating circulation pumps or likewise, it is nowadays counted as belonging to the state of the art, to provide these with a frequency converter which is arranged in a terminal box or frequency converter housing which are mostly attached on the motor housing. Such frequency converters have a multitude of electronic components, from which electromagnetic and/or electrostatic radiation is emitted as an interference source, and these must be shielded, in order to ensure the electromagnetic compatibility (EMC). On the other hand, such frequency converters also comprise sensitive electronic components (susceptible components), in particular of the control and regulation electronics, which are to be protected from electromagnetic and/or electronic influences.
For this, the encasing of the electrical and electronic components forming the power converter with a Faraday cage is counted as belonging to the state of the art.
From DE 297 22 918 U1 it is counted as belonging to the state of the art, to design the complete power converter housing as a Faraday cage.
It can be difficult to ensure the electromagnetic compatibility of the power converter despite such a complete shielding of the power converter by way of a Faraday cage. In practice, this is realized additionally by way of the switching times, especially rise and fall times when switching of the electronics switches being adapted, in order to obtain a lower interfering radiation in particular in the region of higher frequencies. This however has the disadvantage that the efficiency of the converter is decreased, thus losses will increase.
It is also counted as belonging to the state of the art, to arrange interference suppression ferrites beads mounted on the input cable.